Re: I think my book may be wrong about cardinality, but I'm not sure

"beginner16" <kaja_love160_at_yahoo.com> wrote in message news:1185301676.680771.29780_at_b79g2000hse.googlegroups.com...

> 2)
> Relationship between two entities is called binary connection or
> second degree relationship. But connection can exists between more
> than just two entities. Level of connection is determined by the
> number of different entity types that exist in a connection.
>
> Now as far as relational DB goes, don't tables have only binary
> connections ( second degree relationship )?
>

No. An N-degree table implements an N-ary relationship between attributes - attributes which may well identify other entities. Do not assume relationship = foreign key. A foreign key is just one type of constraint (not necessarily the only one) for enforcing referential integrity in RM.

-- 
David Portas